U.S. patent number 10,183,687 [Application Number 15/094,172] was granted by the patent office on 2019-01-22 for pushcart.
This patent grant is currently assigned to MURATA MANUFACTURING CO., LTD.. The grantee listed for this patent is Murata Manufacturing Co., Ltd.. Invention is credited to Masayuki Kubo, Kenichi Shirato.
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United States Patent |
10,183,687 |
Kubo , et al. |
January 22, 2019 |
Pushcart
Abstract
A pushcart includes a steering unit, a main wheel, a dolly
portion, an auxiliary wheel, a connecting unit, a slope angle
sensor, a gyrosensor, and a case. On one end of the steering unit,
there is provided a cylinder-shaped hinge unit that is supported in
a rotatable manner at the other end of the connecting unit on the
opposite side to the main wheels, and a holding portion is provided
on the other end of the steering unit. A controller performs
inverted pendulum control in which the main wheels are rotated
based on the detection results of the gyrosensor and the slope
angle sensor.
Inventors: |
Kubo; Masayuki (Kyoto,
JP), Shirato; Kenichi (Kyoto, JP) |
Applicant: |
Name |
City |
State |
Country |
Type |
Murata Manufacturing Co., Ltd. |
Kyoto |
N/A |
JP |
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Assignee: |
MURATA MANUFACTURING CO., LTD.
(Kyoto, JP)
|
Family
ID: |
52812905 |
Appl.
No.: |
15/094,172 |
Filed: |
April 8, 2016 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20160221594 A1 |
Aug 4, 2016 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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PCT/JP2014/075353 |
Sep 25, 2014 |
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Foreign Application Priority Data
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Oct 11, 2013 [JP] |
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2013-213386 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B62B
3/001 (20130101); B62B 7/042 (20130101); B62B
5/0069 (20130101); B62B 5/068 (20130101); B62B
5/064 (20130101); B62B 3/00 (20130101); A61H
3/04 (20130101); A61H 2201/5007 (20130101); A61H
2003/043 (20130101); A61H 2201/5069 (20130101); A61H
2201/0173 (20130101); B62B 5/0046 (20130101) |
Current International
Class: |
B62B
5/00 (20060101); B62B 5/06 (20060101); B62B
3/00 (20060101); A61H 3/04 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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S62-80709 |
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Apr 1987 |
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JP |
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H09-249129 |
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Sep 1997 |
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JP |
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2003-502002 |
|
Jan 2003 |
|
JP |
|
2004-142734 |
|
May 2004 |
|
JP |
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2011-207277 |
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Oct 2011 |
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JP |
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2012-250569 |
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Dec 2012 |
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JP |
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2013-056601 |
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Mar 2013 |
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JP |
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2012/114597 |
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Aug 2012 |
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WO |
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Other References
Itnernational Search Report issued in Application No.
PCT/JP2014/075353 dated Nov. 11, 2014. cited by applicant .
Written Opinion issued in Application No. PCT/JP2014/075353 dated
Nov. 11, 2014. cited by applicant .
Minami Mamoru et al., "Experiment of Control System, 1. Control of
Inverted Pendulums" dated Nov. 2009;
http://web.archive.org/web/20091108202432/http://www.suri.sys.okayama-u.a-
c.jp/research/experi/experiment.html; retrieved on May 13, 2016.
cited by applicant.
|
Primary Examiner: Black; Thomas G
Assistant Examiner: Smith-Stewart; Demetra R
Attorney, Agent or Firm: Pearne & Gordon LLP
Claims
The invention claimed is:
1. A pushcart comprising: a base unit; a plurality of main wheels
supported by the base unit in a rotatable manner; an auxiliary
wheel supported by the base unit in a rotatable manner about a
rotational shaft which differs from a rotational shaft of the
plurality of main wheels; a driver unit for driving the plurality
of main wheels; a controller for controlling the driver unit; a
connecting unit that is connected to the base unit and extends in a
direction distanced from a ground surface with which the plurality
of main wheels make contact; a steering unit supported in a
rotatable manner in a pitch direction at an end portion of the
connecting unit on an opposite side to the plurality of main
wheels; and an angle change detector for detecting an angle change
in a slope angle of the steering unit in the pitch direction,
wherein the controller controls the driver unit based on output of
the angle change detector so that the angle change of the steering
unit in the pitch direction becomes 0.
2. The pushcart according to claim 1, further comprising: a
blocking unit that prevents the steering unit from rotating at a
predetermined angle or a larger angle.
3. The pushcart according to claim 1, further comprising: a
rotation detector for detecting whether or not the plurality of
main wheels are being rotated, wherein the controller stops driving
of the plurality of main wheels by the driver unit in the case
where the controller determines, based on output of the rotation
detector, that the rotation of the plurality of main wheels is
substantially stopped with the angle change of the steering unit in
the pitch direction being not 0.
4. The pushcart according to claim 1, further comprising: a slope
angle detector for detecting an angle change in a slope angle of
the base unit, wherein the controller calculates, based on output
of the slope angle detector, torque for compensating gravitational
torque due to a slope of the ground surface and controls the driver
unit.
5. The pushcart according to claim 1, wherein an end portion of the
connecting unit on the steering unit side is positioned in a space
that is located in an outer side portion relative to the main
wheels and the auxiliary wheel in a movement direction of the
pushcart moved by the rotation of the plurality of main wheels, and
that is located in the direction opposite to the movement
direction.
6. The pushcart according to claim 1, further comprising: an
adjustment mechanism for adjusting length of one of the connecting
unit and the steering unit.
7. The pushcart according to claim 1, wherein the angle change
detector includes a rotary encoder disposed in a connecting portion
of the connecting unit and the steering unit.
8. The pushcart according to claim 1, wherein the angle change
detector includes at least one of a gyrosensor, a slope angle
sensor, and an acceleration sensor.
9. The pushcart according to claim 2, further comprising: a
rotation detector for detecting whether or not the plurality of
main wheels are being rotated, wherein the controller stops driving
of the plurality of main wheels by the driver unit in the case
where the controller determines, based on output of the rotation
detector, that the rotation of the plurality of main wheels is
substantially stopped with the angle change of the steering unit in
the pitch direction being not 0.
10. The pushcart according to claim 2, further comprising: a slope
angle detector for detecting an angle change in a slope angle of
the base unit, wherein the controller calculates, based on output
of the slope angle detector, torque for compensating gravitational
torque due to a slope of the ground surface and controls the driver
unit.
11. The pushcart according to claim 3, further comprising: a slope
angle detector for detecting an angle change in a slope angle of
the base unit, wherein the controller calculates, based on output
of the slope angle detector, torque for compensating gravitational
torque due to a slope of the ground surface and controls the driver
unit.
12. The pushcart according to claim 2, wherein an end portion of
the connecting unit on the steering unit side is positioned in a
space that is located in an outer side portion relative to the main
wheels and the auxiliary wheel in a movement direction of the
pushcart moved by the rotation of the plurality of main wheels, and
that is located in the direction opposite to the movement
direction.
13. The pushcart according to claim 3, wherein an end portion of
the connecting unit on the steering unit side is positioned in a
space that is located in an outer side portion relative to the main
wheels and the auxiliary wheel in a movement direction of the
pushcart moved by the rotation of the plurality of main wheels, and
that is located in the direction opposite to the movement
direction.
14. The pushcart according to claim 4, wherein an end portion of
the connecting unit on the steering unit side is positioned in a
space that is located in an outer side portion relative to the main
wheels and the auxiliary wheel in a movement direction of the
pushcart moved by the rotation of the plurality of main wheels, and
that is located in the direction opposite to the movement
direction.
15. The pushcart according to claim 2, further comprising: an
adjustment mechanism for adjusting length of one of the connecting
unit and the steering unit.
16. The pushcart according to claim 3, further comprising: an
adjustment mechanism for adjusting length of one of the connecting
unit and the steering unit.
17. The pushcart according to claim 4, further comprising: an
adjustment mechanism for adjusting length of one of the connecting
unit and the steering unit.
18. The pushcart according to claim 5, further comprising: an
adjustment mechanism for adjusting length of one of the connecting
unit and the steering unit.
19. The pushcart according to claim 2, wherein the angle change
detector includes a rotary encoder disposed in a connecting portion
of the connecting unit and the steering unit.
20. The pushcart according to claim 3, wherein the angle change
detector includes a rotary encoder disposed in a connecting portion
of the connecting unit and the steering unit.
Description
BACKGROUND
Technical Field
The present disclosure relates to pushcarts that include wheels and
drive and control the stated wheels.
There are pushcarts that drive and control wheels thereof while
performing inverted pendulum control. For example, Non Patent
Document 1 discloses a dolly that drives and controls wheels
thereof while performing inverted pendulum control.
FIG. 10 is a schematic side view of a dolly 900 disclosed in Non
Patent Document 1. The dolly 900 includes a dolly portion 912, a
front wheel 913, and a rear wheel 911 supported by the dolly
portion 912 in a rotatable manner, and an inverted pendulum 910
supported at the center of the dolly portion 912 in a rotatable
manner.
The dolly 900 maintains a state in which the inverted pendulum 910
stands upright facing the vertical direction by performing inverted
pendulum control for controlling the rotation of the front wheel
913 and the rear wheel 911.
FIGS. 11A and 11B show schematic side views of a pushcart 800
assuming a case where the basic idea of the dolly 900 is applied to
the pushcart. The pushcart 800 includes a plate-like dolly portion
812, a pair of auxiliary wheels 813 supported by the dolly portion
812 in a rotatable manner, a pair of main wheels 811 supported by
the dolly portion 812 in a rotatable manner, and a steering unit
810 supported by the dolly portion 812 in a rotatable manner. The
steering unit 810 corresponds to the above-mentioned inverted
pendulum 910.
One end of the steering unit 810 is supported by an end of the
dolly portion 812 on the main wheel 811 side in a rotatable manner,
and a holding portion 816 is provided on the other end of the
steering unit 810. A user U places a load B on the dolly portion
812, holds the holding portion 816, and then moves the pushcart 800
in a travelling direction P.
The pushcart 800 maintains a state in which the steering unit 810
stands upright facing the vertical direction by performing inverted
pendulum control for controlling the rotation of the main wheels
811. Because of this, even if the user U holds the holding portion
816 and pushes the holding portion 816 in the travelling direction,
the main wheels 811 rotate and the dolly portion 812 also moves in
the travelling direction P, whereby the posture of the steering
unit 810 is maintained to be constant. Non Patent Document 1:
"Experiment of Control System", "1. Inverted Pendulum Control
Experiment", [online]; Feb. 5, 2000; Minami Mamoru and two other
members; [Searched on Jul. 10, 2013], Internet <URL:
http://www.suri.sys.okayama-u.ac.jp/research/experi/experiment.h-
tml>
BRIEF SUMMARY
While taking one end of the steering unit 810 supported at the end
of the dolly portion 812 on the main wheel 811 side as a rotational
shaft, the pushcart 800 is constituted such that the holding
portion 816 on the other end of the steering unit 810 rotates. In
other words, in the case where a length from the above-mentioned
rotational shaft to the other end of the steering unit 810 is taken
as L1, and an angle by which the user U holds the holding portion
816 and pushes the steering unit 810, standing upright in the
vertical direction, in a pitch direction (a rotational direction
about a rotational shaft of the main wheels 811 shown in FIGS. 11A
and 11B) is taken as .theta., a movement distance of the holding
portion 816 is represented as L1sin .theta. (when .theta. is near 0
degree, it takes an approximate value of .theta.L1). The length L1
needs to be set to a value of length in accordance with the height
of the user U to use the pushcart 800.
As such, in the pushcart 800 assuming the application of the
conventional technique, the movement distance L1sin .theta. of the
holding portion 816 is long. Because of this, when the user U holds
the holding portion 816 and moves the pushcart 800, the user U
needs to largely push the holding portion 816 in the pitch
direction. This raises a problem that user-operability of the
pushcart 800 assuming the application of the conventional technique
is not good.
The present disclosure provides a pushcart with improved
user-operability by making the movement distance of the holding
portion shorter than the conventional one.
A pushcart according to the present disclosure includes a base
unit, a plurality of main wheels supported by the base unit in a
rotatable manner, an auxiliary wheel supported by the base unit in
a rotatable manner about a rotational shaft which differs from a
rotational shaft of the plurality of main wheels, a driver unit for
driving the plurality of main wheels, and a controller for
controlling the driver unit.
The pushcart according to the present disclosure further includes a
connecting unit that is connected to the base unit and extends in a
direction being distanced from a ground surface with which the
plurality of main wheels make contact, a steering unit supported in
a rotatable manner in a pitch direction at an end portion of the
connecting unit on the opposite side to the plurality of main
wheels, and an angle change detector for detecting an angle change
in a slope angle of the steering unit in the pitch direction. A
holding portion is provided on an upper end portion of the steering
unit.
The controller controls the driver unit based on output of the
angle change detector so that the angle change of the steering unit
in the pitch direction becomes 0.
In other words, the pushcart of the present disclosure performs
inverted pendulum control in which the angle of the steering unit
in the pitch direction is maintained. Accordingly, the pushcart of
the present disclosure moves in a direction in which the user moves
the holding portion. That is, the pushcart of the present
disclosure moves following the movement of the holding portion
operated by the user. With this, the pushcart of the present
disclosure can give a feeling of safety to the user because of
having the above movement catch-up capability in comparison with a
pushcart that does not perform inverted pendulum control (for
example, a pushcart in which such a technique that moves a vehicle
with lever operation as disclosed in an electric wheelchair of
Japanese Unexamined Patent Application Publication No. 2010-284469
is applied).
While taking one end of the steering unit as a rotational shaft,
the pushcart of the present disclosure is constituted such that the
holding portion on the other end of the steering unit rotates. In
other words, in the case where a length from the above rotational
shaft to the other end of the steering unit is taken as L2, and an
angle by which a user holds the holding portion and pushes the
steering unit, standing upright in the vertical direction, in the
pitch direction is taken as .theta., a movement distance of the
holding portion is represented as L2sin .theta..
The length L2 needs to be set to a value of length in accordance
with the height of a user to use the pushcart of the present
disclosure. Note that the length L2 is shorter than the length L1
of the pushcart 800 assuming the application of the conventional
technique as shown in FIGS. 11A and 11B, by an amount of height of
the connecting unit extending in the direction being distanced from
the ground surface with which the plurality of main wheels make
contact (or an amount of length of the connecting unit in the case
where the connecting unit extends in the vertical direction).
Accordingly, the movement distance L2sin .theta. of the holding
portion of the pushcart of the present disclosure is shorter than
the movement distance L1sin .theta. of the holding portion 816 of
the pushcart 800 assuming the application of the conventional
technique. As such, when a user holds the holding portion and moves
the pushcart of the present disclosure, it is sufficient for the
user to push the holding portion in the pitch direction by a short
distance in comparison with the pushcart 800 assuming the
application of the conventional technique.
Therefore, according to the pushcart of the present disclosure, it
is possible to make the movement distance of the holding portion
shorter than that of the pushcart 800 assuming the application of
the conventional technique, and improve the user-operability.
It is to be noted that the holding portion is not limited to being
supported by the steering unit precisely at the end of the steering
unit, and it is sufficient for the holding portion to be supported
by the steering unit at the end side thereof.
The pushcart according to the present disclosure can further
include a blocking unit that prevents the steering unit from
rotating up to no less than a predetermined angle.
For example, in the case where the auxiliary wheel makes contact
with a step during the pushcart of the present disclosure
travelling, the auxiliary wheel may not ride over the step with
toque of the pushcart of the present disclosure in some case even
if the user rotates the holding portion. In this case, with the
configuration of the present disclosure, the auxiliary wheel and
the main wheels can ride over the step by the user pushing, with
his or her force, the holding portion whose rotation being blocked
at a predetermined angle.
At this time, because the steering unit does not rotate up to no
less than a predetermined angle relative to the vertical direction,
in other words, the torque of the pushcart of the present
disclosure is restricted by the blocking unit, a sudden start of
the push cart of the present disclosure can be prevented
immediately after the auxiliary wheel and the main wheels have
ridden over the step.
Further, even in the case where the power for the pushcart of the
present disclosure is turned off, the user can manually move the
pushcart of the present disclosure by pushing, with his or her
force, the holding portion whose rotation is blocked at a
predetermined angle.
The pushcart according to the present disclosure can further
include a rotation detector for detecting whether or not the
plurality of main wheels are being rotated. Furthermore, the
controller can stop driving of the plurality of main wheels by the
driver unit in the case where the controller determines, based on
output of the rotation detector, that the rotation of the plurality
of main wheels is substantially stopped with the angle change of
the steering unit in the pitch direction being not 0.
With this, in the case where the pushcart of the present disclosure
does not proceed, even if the user pushes the pushcart, because the
auxiliary wheel is caught by a step, wall, or the like, for
example, a motor of the driver unit can be prevented from being
damaged by stopping the driving of the main wheels. Note that
"being substantially stopped" is a state in which the number of
rotations of the main wheel in the pitch direction is lower than a
predetermined threshold.
The pushcart according to the present disclosure can further
include a slope angle detector for detecting an angle change in a
slope angle of the base unit. Furthermore, the controller can
calculate, based on output of the slope angle detector, torque for
compensating gravitational toque due to a slope of the ground
surface and control the driver unit.
In this configuration, even in the case where the pushcart of the
present disclosure is present on a sloping road, because the torque
for compensating the gravitational torque due to a slant of the
sloping road acts on the main wheels, the pushcart of the present
disclosure can be prevented from unintendedly descending the
sloping road.
Further, an end portion of the connecting unit on the steering unit
side can be positioned in a space that is located in an outer side
portion relative to the main wheels and the auxiliary wheel in a
movement direction of the pushcart moved by the rotation of the
plurality of main wheels, and that is also located in the opposite
direction of the above movement direction.
With this configuration, the connecting unit and the steering unit
are slanted so that the steering unit approaches the user side
relative to the main wheels and the auxiliary wheel. This makes it
possible for the user to obtain a wide stepping space. Because of
this, it can prevent the foot of the user from contacting the rear
wheels of the pushcart when the user is pushing and moving the
pushcart, for example.
The pushcart can further include an adjustment mechanism for
adjusting one of lengths of the connecting unit and the steering
unit.
With this configuration, the lengths of the connecting unit and the
steering unit are adjusted in accordance with the height, arm
length, or the like of a user. Further, the adjustment mechanism
can fix the length L2 of the steering unit and only adjust a length
L3 of the connecting unit. Through this, even if the total length
(L2+L3) of the connecting unit and the steering unit is adjusted
only by the length L3 of the connecting unit in accordance with the
height or the like of the user, operability of the holding portion
for the user is maintained because the movement distance
(corresponding to the length L2) of the holding portion supported
at the end portion of the steering unit does not change.
Further, the angle change detector may include a rotary encoder
disposed in a connecting portion of the connecting unit and the
steering unit, or include at least one of a gyrosensor, a slope
angle sensor, and an acceleration sensor.
According to the present disclosure, the movement distance of the
holding portion can be made shorter than the conventional one and
the user-operability can be improved.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
FIG. 1 is a schematic side view of a pushcart 100 according to a
first embodiment of the present disclosure.
FIG. 2 is a schematic rear view of the pushcart 100 shown in FIG.
1.
FIGS. 3A and 3B include schematic side views of the pushcart 100
shown in FIG. 1 when a user U moves the pushcart 100.
FIG. 4 is a control block diagram illustrating a configuration of
the pushcart 100 shown in FIG. 1.
FIG. 5 is a schematic side view of a pushcart 200 according to a
second embodiment of the present disclosure.
FIG. 6 is a schematic side view of a pushcart 300 according to a
third embodiment of the present disclosure.
FIG. 7 is a schematic side view of a pushcart 400 according to a
fourth embodiment of the present disclosure.
FIG. 8 is a schematic side view of a pushcart 500 according to a
fifth embodiment of the present disclosure.
FIG. 9 is a schematic side view of a pushcart 600 according to a
sixth embodiment of the present disclosure.
FIG. 10 is a schematic side view of a pushcart 900 disclosed in Non
Patent Document 1.
FIGS. 11A and 11B include schematic side views of a pushcart 800
assuming the application of a conventional technique.
DETAILED DESCRIPTION
Hereinafter, a pushcart 100 according to a first embodiment of the
present disclosure will be described.
FIG. 1 is a schematic side view of the pushcart 100 according to
the first embodiment of the present disclosure. FIG. 2 is a
schematic rear view of the pushcart 100 shown in FIG. 1. FIGS. 3A
and 3B include schematic side views of the pushcart 100 shown in
FIG. 1 when a user U moves the pushcart 100.
The pushcart 100 includes, as shown in FIGS. 1 and 2, a steering
unit 110, a main wheel 111, a dolly portion 112, an auxiliary wheel
113, a connecting unit 114, a slope angle sensor 20, a gyrosensor
24, and a case 30. The pushcart 100 is used as a shopping cart, a
baby carriage, or a walking assistant cart, for example.
The dolly portion 112 corresponds to "base unit" of the present
disclosure. The gyrosensor 24 corresponds to "angle change
detector" of the present disclosure. The slope angle sensor 20
corresponds to "slope angle detector" of the present
disclosure.
Note that, in order to facilitate understanding of a rotational
state of the steering unit 110, the slope angle sensor 20 and the
gyrosensor 24 are omitted in FIGS. 3A and 3B for convenience.
The dolly portion 112 is formed in a plate-like shape, and the
slope angle sensor 20 is attached to a bottom surface of the dolly
portion 112. Note that a pair of main wheels 111 opposing each
other is supported by the dolly portion 112 in a rotatable manner.
A pair of auxiliary wheels 113 opposing each other is supported by
the dolly portion 112 in a rotatable manner.
Each of the pair of main wheels 111 is independently attached to a
drive shaft, and is driven separately and rotated. However, the
pair of main wheels 111 can be rotated in synchronization with each
other. In the present embodiment, although an example in which the
main wheels 111 take the form of two wheels is cited, the
disclosure is not limited to the form of two wheels. Likewise,
although an example in which the auxiliary wheels 113 take the form
of two wheels is cited in the present embodiment, the disclosure is
not limited to the form of two wheels.
To an end of the dolly portion 112 on the main wheel 111 side, one
end of the connecting unit 114 configured of two bar-like members
extending in the vertical direction is connected.
Although the connecting unit 114 extends in the vertical direction
in the pushcart 100, the disclosure is not limited thereto. It is
sufficient that the connecting unit 114 extends in a direction
being distanced from a ground surface G with which the pair of main
wheels 111 makes contact (for example, see FIG. 6 to be explained
later).
The gyrosensor 24 is attached to the steering unit 110. On one end
of the steering unit 110, there is provided a cylinder-shaped hinge
unit 115 that is supported in a rotatable manner by one end of the
connecting unit 114 on the opposite side to the main wheels 111,
and a holding portion 116 is provided on the other end of the
steering unit 110. Note that the hinge unit 115 is not limited to
the cylinder shape.
In the hinge unit 115, there is provided a blocking mechanism that
prevents the steering unit 110 from rotating up to no less than a
predetermined angle relative to the vertical direction (for
example, 30 degrees in a forward direction and backward direction,
respectively).
In the holding portion 116, a user interface (a user I/F 28 shown
in FIG. 4) including a power switch of the pushcart 100 and the
like is provided. As shown in FIGS. 3A and 3B, a user U holds the
holding portion 116 from a side opposite to the auxiliary wheels
113 after having placed a load B on the dolly portion 112 or places
the forearms or the like on the holding portion 116, and then moves
the pushcart 100 in the forward or backward direction on the ground
surface G.
The case 30 (not shown in FIGS. 3A and 3B) is mounted on the dolly
portion 112 and stores a control circuit board, a battery, and the
like.
Next, the configuration and basic operations of the pushcart 100
will be described.
FIG. 4 is a control block diagram illustrating the configuration of
the pushcart 100 shown in FIG. 1. The pushcart 100 includes the
slope angle sensor 20, a controller 21, a ROM 22, a RAM 23, the
gyro sensor 24, a driver unit 25, the rotary encoder 26, and the
user I/F 28.
Note that the rotary encoder 26 corresponds to "rotation detector"
of the present disclosure.
The controller 21 is a functional unit configured to integrally
control the pushcart 100, and realizes various kinds of operations
by reading out programs stored in the ROM 22 and loading these
programs in the RAM 23.
The rotary encoder 26 detects a rotational angle of the main wheels
111 and outputs the detected result to the controller 21. The
controller 21 differentiates the rotational angle of the main
wheels 111 inputted from the rotary encoder 26 and calculates an
angular velocity of the main wheels 111.
The slope angle sensor 20 detects a slope angle of the dolly
portion 112 relative to the vertical direction and outputs the
detected result to the controller 21.
The gyrosensor 24 detects an angular velocity of the steering unit
110 in the pitch direction (a rotational direction about a
rotational shaft of the hinge unit 115 shown in FIG. 1) and outputs
the detected result to the controller 21.
Although an example in which the rotary encoder 26 is used as a
method to detect whether or not the main wheels 111 are rotated is
cited in the present embodiment, the disclosure is not limited
thereto and any other sensors may be used instead.
Likewise, in the present embodiment, although an example in which
the slope angle sensor 20 is used as a slope angle detector to
detect an angle change in the slope angle of the dolly portion 112
is described, the disclosure is not limited thereto. For example,
it is sufficient that the slope angle detector of the present
disclosure is realized by using at least one of a slope angle
sensor, an acceleration sensor, and a gyrosensor.
Likewise, in the present embodiment, although an example in which
the gyrosensor 24 is used as an angle change detector to detect an
angle change in the slope angle of the steering unit 110 in the
pitch direction is described, the disclosure is not limited
thereto. It is sufficient that the angle change detector of the
present disclosure is realized by including at least one of a
gyrosensor, a slope angle sensor, and an acceleration sensor. For
example, in the case where a slope angle sensor (not shown) is
provided in place of the gyrosensor 24 on the steering unit 110,
the slope angle of the steering unit 110 detected by the stated
slope angle sensor is differentiated and then a slope angular
velocity of the steering unit 110 is calculated. Further, as
another example, the pushcart 100 may include a rotary encoder in
the hinge unit 115 and detect the slope angle of the steering unit
110 in the pitch direction based on the detection result of the
above rotary encoder.
In the case where the pushcart 100 includes a plurality of sensors
as the slope angle detector, the controller 21 may compare the
detection results from the plurality of sensors and determine that
a failure has occurred in one of the sensors if there exists a
difference among the plurality of detection results. Likewise, in
the case where the pushcart 100 includes a plurality of sensors to
realize the angle change detector, the controller 21 may determine,
through comparing the detection results from the plurality of
sensors, that a failure has occurred in one of the sensors.
Then, based on the detection results of the gyrosensor 24 and the
slope angle sensor 20, the controller 21 performs inverted pendulum
control in which the main wheels 111 are rotated by the driver unit
25 so that the angle change of the steering unit 110 in the pitch
direction becomes 0 and the slope angle of the steering unit 110
relative to the vertical direction comes to a target value (for
example, 0 or nearly 0).
The above-mentioned inverted pendulum control will be described in
detail hereinafter.
The controller 21 calculates a slope angle of the dolly portion 112
based on the detection result of the slope angle sensor 20. Through
this, the controller 21 estimates a slope angle of the ground
surface G, on which the pushcart 100 is present, relative to the
vertical direction. For example, in the case where the pushcart 100
is present on a sloping road, gravitational torque due to a slant
of the sloping road (a slope angle of the ground surface G relative
to the horizontal surface) acts on the main wheels 111 and causes
the pushcart 100 to unintendedly descend the sloping road.
As such, the controller 21 calculates a first torque value to
compensate the gravitational torque based on the slope angle of the
dolly portion 112. Note that in the case where the pushcart 100 is
present on a flat road with the slant being 0 degree, the first
torque value is 0.
Further, the controller 21 calculates a slope angular velocity of
the steering unit 110 based on the detection result of the
gyrosensor 24. Furthermore, the controller 21 calculates a slope
angle of the steering unit 110 by integrating the slope angular
velocity of the steering unit 110.
The controller 21 calculates a differential value between a preset
target slope angle (for example, 0 degree) and a current slope
angle of the steering unit 110 having been calculated based on the
detection result of the gyrosensor 24, and then calculates a target
value of the slope angular velocity of the steering unit 110 that
can make the above differential value become 0. Subsequently, the
controller 21 calculates a differential value between the
calculated target value of the slope angular velocity and a current
slope angular velocity of the steering unit 110 having been
calculated based on the detection result of the gyrosensor 24, and
then calculates a second torque value that can make the above
differential value become 0.
Subsequently, the controller 21 calculates a third torque in which
the first torque and second torque having been calculated are
combined, and outputs the calculation result to the driver unit
25.
The driver unit 25 drives a motor for rotating a shaft attached to
the pair of main wheels 111. The driver unit 25 applies the torque
value inputted from the controller 21 to the motor of the main
wheels 111 so as to rotate the main wheels 111.
As discussed above, the pushcart 100 performs the inverted pendulum
control to maintain a state in which the steering unit 110 stands
upright facing the vertical direction. As such, even in the case
where a user holds the holding portion 116 and pushes the holding
portion 116 in a forward direction P, the main wheels 111 rotate
and the dolly portion 112 also moves in the forward direction P so
that the posture of the steering unit 110 is maintained to be
constant. Conversely, in the case where the user holds the holding
portion 116 and pulls the holding portion 116 in the backward
direction, the main wheels 111 rotate and the dolly portion 112
also moves in the backward direction so that the posture of the
steering unit 110 is maintained to be constant.
By performing the inverted pendulum control, the pushcart 100 moves
in a direction in which the user U moves the holding portion 116.
In other words, the pushcart 100 moves following the movement of
the holding portion 116 caused by the operation of the user U. With
this, the pushcart 100 can give a feeling of safety to the user U
because of having the above movement catch-up capability in
comparison with a pushcart that does not perform inverted pendulum
control (for example, a pushcart moved by the lever operation).
Further, for example, even in the case where the pushcart 100 is
present on a sloping road, because torque for compensating the
gravitational torque due to the slant of the sloping road acts on
the main wheels 111, the pushcart 100 can be prevented from
unintendedly descending the sloping road.
The controller 21 stops the driving of the main wheels 111 by the
driver unit 25 in the case where the controller 21 determines,
based on the output of the gyrosensor 24 and the output of the
rotary encoder 26, that the rotation of the main wheels 111 is
stopped in a state in which the angle change of the steering unit
110 in the pitch direction is not 0. This makes it possible to
prevent the motor of the driver unit 25 from being damaged by
stopping the driving of the main wheels 111 in the case where the
auxiliary wheels 113 are caught by a step, wall, or the like and do
not proceed even if the user U pushes the pushcart 100. However,
the controller 21 may stop the driving of the main wheels 111 by
the driver unit 25 not only when the number of rotations of the
main wheels 111 is precisely 0, but also when the number of
rotations of the main wheels 111 in the pitch direction is lower
than a predetermined threshold 1. In other words, the controller 21
may stop the driving of the main wheels 111 in the case where the
rotation of the main wheels 111 is substantially stopped in a state
where the angle change of the steering unit 110 in the pitch
direction is not 0.
Moreover, in the case where the number of rotations of the main
wheels 111 in the pitch direction is higher than a predetermined
threshold 2 (note that, threshold 2>threshold 1), the controller
21 may also stop the driving of the main wheels 111 by the driver
unit 25. For example, the pushcart 100 stops the driving of the
main wheels 111 in consideration of safety in the case where the
main wheels 111 spin due to slipping and the number of rotations of
the main wheels 111 becomes higher than the threshold 2.
In the configuration discussed above, while taking the hinge unit
115 on one end of the steering unit 110 as a rotational shaft, the
pushcart 100 is constituted such that the holding portion 116 on
the other end of the steering unit 110 is rotated. That is, in the
case where a length from the stated rotational shaft to the other
end of the steering unit 110 is taken as L2, and an angle by which
the user U holds the holding portion 116 and pushes the steering
unit 110, standing upright in the vertical direction, in the pitch
direction is taken as .theta., the movement distance of the holding
portion 116 is represented as L2sin .theta..
The length L2 needs to be set to a length in accordance with the
height of the user U to use the pushcart 100. However, the length
L2 is shorter than the length L1 of the pushcart 800 assuming the
application of the technique as shown in FIGS. 11A and 11B, by an
amount of length of the connecting unit 114 extending in the
vertical direction.
Accordingly, the movement distance L2sin .theta. of the holding
portion 116 of the pushcart 100 is shorter than the movement
distance L1sin .theta. of the holding portion 816 of the pushcart
800 assuming the application of the conventional technique. As
such, when the user U holds the holding portion 116 and moves the
pushcart 100, it is sufficient for the user U to push the holding
portion 116 in the pitch direction by a short distance in
comparison with the pushcart 800 assuming the application of the
conventional technique.
Therefore, according to the pushcart 100, it is possible to make
the movement distance L2sin .theta. of the holding portion 116
shorter than that in the pushcart 800 assuming the application of
the conventional technique, and improve the user-operability.
As discussed above, because the blocking mechanism is provided in
the hinge unit 115, the steering unit 110 does not rotate up to no
less than a predetermined angle relative to the vertical direction
(for example, 30 degrees in the forward direction and backward
direction, respectively).
To be more specific, for example, there is a case where the
auxiliary wheels 113 make contact with a step during the travelling
of the pushcart 100 and cannot ride over the step with the torque
of the pushcart 100 even if the user U rotates the holding portion
116. In this case, the auxiliary wheels 113 and the main wheels 111
can ride over the step by the user U pushing, with his or her
force, the holding portion 116 whose rotation is blocked at a
predetermined angle.
At this time, because the steering unit 110 does not rotate up to
no less than a predetermined angle relative to the vertical
direction, in other words, the torque of the pushcart 100 is
restricted by the blocking mechanism, a sudden start of the
pushcart 100 can be prevented immediately after the auxiliary
wheels 113 and the main wheels 111 have ridden over the step.
In addition, for example, even in the case where the power of the
pushcart 100 is turned off, the user U can manually move the
pushcart 100 by pushing, with his or her force, the holding portion
116 whose rotation is blocked at a predetermined angle. At this
time, a connecting portion of the steering unit 110 and the holding
portion 116 is fixed in an initial state (a state of being not
operated). This makes it easy for the user U to hold the holding
portion 116 and manually move the pushcart 100.
Hereinafter, a pushcart 200 according to a second embodiment of the
present disclosure will be described.
FIG. 5 is a schematic side view of the pushcart 200 according to
the second embodiment of the present disclosure.
The pushcart 200 of the second embodiment differs from the pushcart
100 of the first embodiment in a point that a supporter 212 is
included therein in place of the dolly portion 112. The supporter
212 is formed in a rectangular frame shape, and the pair of
auxiliary wheels 113 opposing to each other is supported by the
supporter 212 in a rotatable manner. The connecting unit 114 is
connected to an end of the supporter 212 on the opposite side to
the auxiliary wheels 113. In the pushcart 200, the supporter 212
corresponds to "base unit" of the present disclosure. The pushcart
200 is used as a baby carriage, for example. Since other
constituent elements are the same as those of the pushcart 100,
descriptions thereof are omitted herein.
Hereinafter, a pushcart 300 according to a third embodiment of the
present disclosure will be described.
FIG. 6 is a schematic side view of the pushcart 300 according to
the third embodiment of the present disclosure.
The pushcart 300 of the third embodiment differs from the pushcart
100 of the first embodiment in a point that an end of the
connecting unit 114 on the steering unit 110 side is positioned in
a space that is located in an outer side portion relative to the
main wheels 111 and the auxiliary wheel 113 in the forward
direction P, and that is also located in the opposite direction of
the forward direction P (backward direction). In the pushcart 300,
the connecting unit 114 extends in a direction being distanced from
the ground surface G with which the main wheels 111 make contact.
Since other constituent elements are the same as those of the
pushcart 100, descriptions thereof are omitted herein.
In the pushcart 300, the holding portion 116 more approaches the
user U side than that in the pushcart 100 shown in FIGS. 3A and 3B.
With this, in the case of the pushcart 300, a stepping space S for
the user U is spread wider than the case of the pushcart 100 shown
in FIGS. 3A and 3B. Because of this, it can prevent the foot of the
user U from contacting the main wheels 111 of the pushcart 300 when
the user U is pushing and moving the pushcart 300, for example.
Hereinafter, a pushcart 400 according to a fourth embodiment of the
present disclosure will be described.
FIG. 7 is a schematic side view of the pushcart 400 according to
the fourth embodiment of the present disclosure.
As shown in the schematic side views of FIG. 6 and FIG. 7, the
pushcart 400 of the fourth embodiment differs from the pushcart 300
of the third embodiment in a point that the connecting unit 114 is
curved so that a portion thereof on the opposite direction side of
the forward direction P becomes a bent outer circumference
side.
In the pushcart 400, although the connecting unit 114 is formed in
a curved shape, the holding portion 116 more approaches the user U
than that in the pushcart 100 shown in FIGS. 3A and 3B, and the
stepping space S is spread wider.
Hereinafter, a pushcart 500 according to a fifth embodiment of the
present disclosure will be described.
FIG. 8 is a schematic side view of the pushcart 500 according to
the fifth embodiment of the present disclosure.
The pushcart 500 of the fifth embodiment differs from the pushcart
100 of the first embodiment in a point that the pushcart 500
includes an adjustment mechanism for adjusting the length of the
connecting unit 114.
The adjustment mechanism is, for example, a retractable pipe whose
length is fixedly set by hand or fixedly set length is released
also by hand. However, the adjustment mechanism may be a mechanism
configured to automatically adjust the length of the connecting
unit 114 using a motor.
In the case where a length from the rotational shaft of the main
wheels 111 to the rotational shaft of the hinge unit 115 is taken
as L3, the length L3 corresponds to the length of the connecting
unit 114. For example, as shown in FIG. 8, by making a length L3'
of the pushcart 500 shorter than the length L3 of the pushcart 100
shown in FIGS. 3A and 3B, a height from the ground surface G to the
holding portion 116 (corresponds to the sum of L2 and L3) becomes
lower than the height of the pushcart 100 shown in FIGS. 3A and 3B,
corresponding to a user U' shorter in height than the user U.
Conversely, although not shown, by making the length L3' of the
pushcart 500 longer than the length L3 of the pushcart 100 shown in
FIGS. 3A and 3B, the height from the ground surface G to the
holding portion 116 can be made higher than the height of the
pushcart 100 shown in FIGS. 3A and 3B, corresponding to the user U'
taller than the user U.
Further, the length L2 of the pushcart 500 equals the length L2 of
the pushcart 100 shown in FIGS. 3A and 3B. This makes a movement
distance L2sin .theta. of the holding portion 116 in the pushcart
500 equal to the movement distance L2sin .theta. of the holding
portion 116 in the pushcart 100. Accordingly, even if the total
length (L2+L3) of the connecting unit 114 and the steering unit 110
is changed, operability for the user U' that moves the holding
portion 116 is maintained because the movement distance L2sin
.theta. of the holding portion 116 is unchanged.
Note that, however, the adjustment mechanism in the present
embodiment may be a mechanism configured to adjust the length
L2.
Although all of the pushcarts 100, 200, and 300 include the
auxiliary wheels 113 in front and the main wheels 111 in back as
drive wheels, the disclosure is not limited thereto. For example,
by exchanging the positions of the main wheels 111 and the
auxiliary wheels 113, the main wheels 111 as the drive wheels may
be provided in front and the auxiliary wheels 113 may be provided
in back.
For example, as shown in a schematic side view of FIG. 9, in a
pushcart 600 according to a sixth embodiment of the present
disclosure, the main wheels 111 are positioned in front of the
auxiliary wheels 113 in the forward direction P.
To be more specific, as shown in the schematic side view of FIG. 9,
the connecting unit 114 is slanted so that the hinge unit 115 is
positioned at the opposite direction side of the forward direction
P. The controller 21 takes a direction along an extension direction
of the slanted connecting unit 114 as a reference direction, and
performs inverted pendulum control so that an angle change in the
pitch direction relative to the reference direction becomes 0.
The pushcart 600 includes a supporter 117 that extends from the
rotational shaft of the auxiliary wheels 113 in a direction being
distanced from the ground surface G. An end portion of the
supporter 117 on the opposite side to the auxiliary wheels 113 is
supported by the hinge unit 115. However, it is not absolutely
necessary to include the supporter 117.
Because the pushcart 600 according to the sixth embodiment of the
present disclosure is a front drive pushcart, even if the front
wheel (main wheel 111) makes contact with a step, the pushcart 600
is likely to ride over the step in comparison with a rear drive
pushcart.
Lastly, the descriptions of the above embodiments are merely
examples in all ways and should be understood not to be limiting in
any ways. The scope of the present disclosure is defined by the
appended claims rather than by the aforementioned embodiments.
Further, any meanings equivalent to the appended claims as well as
all modifications made within the scope of the appended claims are
intended to be encompassed in the scope of the present
disclosure.
REFERENCE SIGNS LIST
20 SLOPE ANGLE SENSOR 21 CONTROLLER 22 ROM 23 RAM 24 GYROSENSOR 25
DRIVER UNIT 26 ROTARY ENCODER 30 CASE 100 PUSHCART 110 STEERING
UNIT 111 MAIN WHEEL 112 DOLLY PORTION 113 AUXILIARY WHEEL 114
CONNECTING UNIT 115 HINGE UNIT 116 HOLDING PORTION 117 SUPPORTER
200 PUSHCART 212 SUPPORTER 300, 400, 500, 600 PUSHCART 800 PUSHCART
810 STEERING UNIT 811 MAIN WHEEL 812 DOLLY PORTION 813 AUXILIARY
WHEEL 816 HOLDING PORTION 900 DOLLY 910 INVERTED PENDULUM 911 REAR
WHEEL 912 DOLLY PORTION 913 FRONT WHEEL B LOAD G GROUND SURFACE S
STEPPING SPACE U USER
* * * * *
References